1. Field of the Invention
The present invention relates to a motor with power-generating coil set and, more particularly, to a motor having a thin structure.
2. Description of the Related Art
Referring to FIG. 1, an invention of a Taiwan patent with patent number I347166 and entitled as “Cooling Fan” is shown and regards to a cooling fan including a base 91, a fan wheel 92, a driving unit 93 and a power-generating unit 94. The base 91 has a shaft tube 911. The fan wheel 92 is rotatably coupled with the shaft tube 911 and has a carrier 921, with an end edge of the carrier 921 extending towards the base 91 to form an annular wall 922. The driving unit 93 includes a first magnet ring 931 and a first coil 932, wherein the first magnet ring 931 is mounted on an inner surface of the annular wall 922, the first coil 932 surrounds the shaft tube 911, and there is a first air gap “A1” between the first magnet ring 931 and the first coil 932. The power-generating unit 94 includes a second magnet ring 941 and a second coil 942, wherein the second magnet ring 941 is mounted on the shaft tube 911 and adjacent to the carrier 921, the second coil 942 is mounted on an lower surface of the carrier 921, and there is a second air gap “A2” between the second magnet ring 941 and the second coil 942.
When the cooling fan runs, the first coil 932 is electrically energized to generate an alternating magnetic field so as to drive the first magnet ring 931, and thus the fan wheel 92 turns. At the same time, the second coil 942 is moved relatively to the second magnet ring 941 by the rotation of the fan wheel 92, and thus the second coil 942 generates an induced current by the magnetic field of the second magnet ring 941 due to flux linkage.
However, in order to serve as a motor and a power generator simultaneously, in comparison with other fans, this conventional cooling fan has not only the driving unit 93 but also the power-generating unit 94. Therefore, an axial length of the cooling fan includes not only the axial width of the first air gap “A1” but also the axial width of the second air gap “A2.” Specifically, since the first air gap “A1” and second air gap “A2” are arranged in different axial positions of the cooling fan, this cooling fan is axially thicker than other fans not providing a power-generating function owing to the additional second air gap “A2”. Similarly, because the first magnet ring 931 and first coil 932 for fan driving and the second magnet ring 941 and second coil 942 for power generation are arranged in stagger axially, this conventional cooling fan is thus complex in structure and it is impossible to further reduce its axial size.